As I understand it you burn fat and spare muscle by either doing cardio at a lower heart rate for a longer duration or by using the HIIT method which is high intensity interval training which means going at a slower rate for a few minutes then pretty much as fast as you can for like a minute and alternate the two and do that for a short period of time like 10 or 15 minutes. Going at a medium bpm for a long duration is likely to burn muscle as well as fat and depending on your case that may or may not be an issue for you but most would prefer to burn mostly fat and leave the muscle alone.

As far as BMI goes I think it's a crock. It will overestimate body fat % in athletes and those that have muscular builds and will underestimate fat % in older persons or those that have lost muscle mass.

I agree. You'll want to keep the muscle you have if you want to lose fat and keep it off. Otherwise you'll fall into a cycle of killing your metabolism. Also note that DIET MUST BE IN ORDER or all the cardio in the world will do you no good. Clean foods and a calorie deficit will really make all the difference.

I agree that you shouldn't put too much trust in BMI as it only relies on weight and height and makes no allowance at all for body composition, age, muscle mass. This same problem applies to all height/weight charts. Measuring body fat % is the most accurate way to assess if you are overweight or not.

Your body will also get used to whatever workout you do if you are doing the same thing every session. An hour at a constant pace is great for cardiovascular fitness but not optimal for fat loss. I suggest also changing machines, speeds, difficulties and durations to keep your body guessing.

I found the elliptical trainer was a lot harder work than the arc machine and definitely more challenging. The elliptical machines at my gym also have an Interval Training program which alternates between high and low resistance. You can alternate between both machines, add the bikes, steppers, even rowing machines for good cardio and fat loss workout variations. Also the more variety of exercises you do, the less chance you have of getting bored.

Thanks ...
I agree that BMI doesn't seem to be working .... I started doing 30-60 miutes of cardio 5X per week and 4X weightlifting and have lost two inches on the waist ... but my weight has only gone down 5 lbs.

I'll try interval method and see if that works any better. And yes ... the diet ... I need some work there ... I eat lots of lean protein ... problem is LOTS ... portion control is my trouble. got to get that under control also.

I started doing 30-60 miutes of cardio 5X per week and 4X weightlifting and have lost two inches on the waist ... but my weight has only gone down 5 lbs.

This is what you want to see happen when working toward fat loss. It means that you are building lean muscle and burning fat. Getting leaner, but maintaining lean mass. Your metabolism should be going like a furnace!